On top what was already answered, stands for me the strategic view of logistics from end to end: From supplier, through own production until customer delivery. Both information logistics (ordering, forecasting) and physical logistics (warehouse, transport, packaging, foreign trade) must always have this bird view in their mind.
That explains the importance of logistics in a company organization: functions that are often valued as much more important such as purchasing, sales, production, etc. only focus on a portion of this end-to-end supply chain.
Only logistics brings it all together so products and services can flow.